Luận án tiến sĩ: Tích hợp khoa học khí hậu vào chính sách nước tại lưu vực sông Vu Gia-Thu Bon - Nghiên cứu của Tra Van Tran tại TU Dortmund

Translating Climate Science into Policy Making in the Water Sector for the Vu Gia- Thu Bon River Basin A DOCTORATE DISSERTATION SUBMITTED IN FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF ENGINEERING Prepared by: Tra Van Tran Dissertation Committee: Supervisor: Univ. Nguyen Xuan Thinh Supervisor: apl. Stefan Greiving Examiner: Univ. Dietwald Gruehn Dortmund, March 2018 Printed with the support of the German Academic Exchange Service ACKNOWLEDGEMENT With great pleasure, I would like to acknowledge the roles of several individuals and organizations who were instrumental to the completion of my Ph.

Without them, the research would have never seen the light of day. Firstly, I would like to express my sincere appreciation to my supervisor Prof. Nguyen Xuan Thinh, you have been a great mentor to me. I would like to thank you for supervising my research and your support during my entire research stay at RIM.

I am forever grateful. I further wish to express my deep sense of gratitude towards my second supervisor, Prof. I thank you for your valuable input towards my research and all the time and support you have given me for this research that made it possible. I am grateful towards Prof.

Dietwald Gruehn- Chairperson of the Ph. Committee at the Faculty of Spatial Planning, TU Dortmund University who accepted to be the chairperson for my exam committee. Your support during the submission of my thesis and your time during the oral examination made the publication of my results possible. My deepest appreciation belongs to my family including my father, my mother, and my sister for their support, patience, and understanding throughout the duration of my study.

I would like to further acknowledge Dr. Nguyen Xuan Hien- Director and Mr. Khuong Van Hai at the Center for Marine Hydro-Meterological Research and the research members at the Center for their valuable technical input and assistance. I am deeply grateful to Associate Prof.

Nguyen Van Thang- Director General, Associate Prof. Huynh Thi Lan Huong- Deputy Director General, Dr. Mai Van Khiem- Deputy Director General, Mr. Nguyen Van Dai, and Mr.

Ha Truong Minh, at the Viet Nam Institute of Meteorology, Hydrology and Climate Change for their supporting role in climate change General Circulation Models, and the development of the hydrological model package. I would like to recognize the important roles of Associate Prof. Tran Hong Thai- Deputy Director General of the Viet Nam National Hydro- Meteorological Services, i and Mr. Dinh Phung Bao- director of the Central Regional Hydro- Meteorological Center for authorizing the use of hydrological and meteorological data.

I am thankful for the support received from Mr. Luu Duc Dung, Secretary to the “National Scientific Program on Natural Resources, Environment and Climate Change” standing office, and Mr. Nguyen Ngoc Han at the Viet Nam Institute for Fishery and Economic Planning” for their supporting role in the remote sensing aspect in my research. I would also like to acknowledge the support I received from both staff members and fellow Ph.

students at RIM Department at the Faculty of Spatial Planning, TU Dortmund University especially Mustafa, Haniyeh, Matthias, Jacob, Florian, Van and Kiet. It has been a great three years and a great pleasure for me to be completing my research with such a great team. I further acknowledge the World Climate Research Program’s Working Group on Coupled Modelling, which is responsible for CMIP, and I thank the climate modeling groups for producing and making their model output available. Finally, the work would not materialize without the financial support from the DAAD NaWaM Program, and the German Federal Ministry of Education and Research (BMBF).

ii ABSTRACT Vu Gia- Thu Bon River Basin, located in the Central Coastal Zone of Viet Nam faces water shortage problems. This is expected to be further exacerbated in the future as a result of climate change. Previous attempts in addressing water shortage in the area followed a traditional top-down, predict-then-act approach. In such an approach, General Circulation Model outputs simulating future climate conditions are downscaled then adaptation measures proposed.

This approach could produce optimal adaptation solution under an intended future. However, given the uncertainties related to GCMs, the approach fails to provide satisfactory information for adaptation measures. This study utilizes a combined top-down and bottom-up climate change impact assessment instead. A MIKE BASIN water balance model is used to analyze the water system response in the Vu Gia- Thu Bon River Basin under different rainfall and temperature ranges.

Problematic conditions were then identified. Outputs from 25 GCMs were used to map the vulnerability space of the water system onto possible future climate conditions. A more detailed analysis of the system is thus performed only on problematic conditions suggesting both by the MIKE BASIN model and the GCM outputs. An analysis of the effects of current land use policy was performed to assist in the understanding of the changes in land policy and its effect on water usage.

This was done through analyzing satellite images between the years 2011 and 2016 during the land use master plan period of 2011-2020. The results obtained in the study suggest that at a minimum, 66.36 km2 of agricultural area would be facing water challenges in the future. Under more severe climate change conditions, up to 87.77 km2 of crops would be facing water shortages. Overall, there is a water deficit of between approximately 11 million and 21 million m 3 of water for agricultural production.

To meet the demand, the study proposes two lines of action, namely conserve/reduce use of water, and production of additional water. Conserving/reducing water usage could be achieved through changing crop types, irrigation practice, and introducing water efficient technologies. On the other hand, production of additional water includes the construction of more water reservoirs as well as to look into options such as seawater desalination. iii iv TABLE OF CONTENTS Acknowledgement.

iii Table of Contents. v List of Figures. ix List of Tables. 12 List of Abbreviations .2 Research Questions and Objectives .3 Structure of the Report .1 Climate Change Background .1 Climate and weather .2 Causes of climate change .3 Climate Change Modeling and Projections .2 Water Shortages and Climate Change .1 Process- driven modelling .2 Data- driven modelling .3 Conceptual hydrological models .4 Climate Change Impact Assessment Approaches .1 Top-down climate change assessment .2 Bottom-up climate change assessment .3 Combination of top-down and bottom-up approaches.

39 3 Study Area and Selection Justification .1 Overview of Study Area .2 Climate Variability and Extreme Weather Events .3 Previous Relevant Research in the Area .4 Research Gap and Justification .1 Hydrological and meteorological data .2 General circulation model outputs .3 Socio-economic data .4 Satellite image data .1 Identification of Climate Hazard and Threshold .2 Rainfall-runoff model .3 Water demand model .3 Climate Risk Discoveries .4 Tailoring Climate Information to Assist Decision Making .5 Current Status and Effects of Land Use Policies. 82 5 Results and Discussions .1 Climate Hazards and Thresholds.1 Rainfall-runoff model .2 Water demand model .3 Climate Risks Discoveries .1 Baseline results without upstream reservoir .2 Baseline results with upstream reservoir .3 Climate vulnerability space.4 Tailoring Climate Information to Assist Decision Making .5 Current Status and Effects of Land Use Policies .2 Land cover change results .6 Adaptation Policy Proposal .1 Fulfilling Research Objectives.2 Limitations of the Research. 159 Appendix A: List of CMIP5 models used. 159 Appendix B: SWSI values for drought years.

160 vii viii LIST OF FIGURES Figure 2-1: Main drivers of climate change (IPCC, 2007a). 23 Figure 2-2: Schematic of a GCM grid (IPCC, 2013b). 26 Figure 2-3: Runoff processes (US Army Corps of Engineers, 2000). 33 Figure 2-4: Top- down approach (Dessai and Hulme, 2004).

36 Figure 2-5: Bottom-up approach (Dessai and Hulme, 2004). 38 Figure 2-6: Scenario-neutral conceptual framework (Prudhomme et al. 39 Figure 2-7: Conceptual framework used by Wilby and Dessai (2010). 40 Figure 2-8: Framework from Bhave et al.

41 Figure 2-9: Future Visioning Process (Shaw et al., 2009; Sheppard et al. 42 Figure 2-10: The Decision Scaling Framework (Brown et al. 43 Figure 3-1: Location of the study area. 46 Figure 3-2: Topography of the study area.

47 Figure 3-3: Average monthly rainfall and evaporation (data source: IMHEN). 49 Figure 3-4: Uncertainties in a top-down approach (Wilby and Dessai, 2010). 55 Figure 3-5: Monitoring stations in the Vu Gia- Thu Bon River Basin. 57 Figure 3-6: High Resolution SPOT image for Da Nang City.

59 Figure 4-1: Overall Workflow of the research. 62 Figure 4-2: MIKE BASIN sub-basin delineation. 65 Figure 4-3: MIKE NAM processes and parameters. 66 Figure 4-4: Location of Nong Son and Thanh My catchments.

70 Figure 4-5: Irrigation zones in the MIKE BASIN model. 73 Figure 4-6: Schematic of important reservoir inputs. 78 Figure 4-7: Visualization of bi-linear interpolation. 81 Figure 4-8: Hierarchy classification scheme for land cover mapping.

86 ix Figure 4-9: Confusion matrix post classification. 87 Figure 4-10: Ground reference points for accuracy assessment. 88 Figure 5-1: SWSI of 1998 in comparison with other drought years. 93 Figure 5-2: Runoff at Nong Son gauge following the calibration process.

94 Figure 5-3: Runoff at Nong Son gauge following the validation process. 94 Figure 5-4: Runoff at Thanh My gauge following the calibration process. 95 Figure 5-5: Runoff at Thanh My gauge following the validation process. 95 Figure 5-6: MIKE BASIN model fully developed.

102 Figure 5-7: Water supply reliability without upstream reservoirs (baseline period) 103 Figure 5-8: Water supply reliability with upstream reservoirs (baseline period). 104 Figure 5-9: Reliability of node IRR_VG07. 106 Figure 5-10: Reliability of node IRR_VG09. 106 Figure 5-11: Reliability of node IRR_VG12.

107 Figure 5-12: Reliability of node IRR_VG13. 108 Figure 5-13: Reliability of node IRR_TB09. 109 Figure 5-14: Reliability of node IRR_TB13. 109 Figure 5-15: Reliability of node IRR_TB15.

110 Figure 5-16: Reliability of node IRR_TB21. 111 Figure 5-17: Reliability of node IRR_VG23. 111 Figure 5-18: VGTB land cover in 2011 using supervised classification. 118 Figure 5-19: VGTB land cover in 2016 using supervised classification.

119 Figure 5-20: VGTB land cover in 2011 using index-based approach. 120 Figure 5-21: VGTB land cover in 2016 using index based approach. 121 Figure 5-22: Example of empty-land covered with vegetation. 122 Figure 5-23: Comparison of Landsat 8 and SPOT 7 Images.

124 Figure 5-24: Paddy rice area converted in between 2011 and 2016. 127 x Figure 5-25: Conversion of agricultural area into built-up area. 128 Figure 5-26: Conversion of agricultural land into water bodies. 131 Figure 5-27: Conversion of agricultural area into vegetation.

132 Figure 5-28: Conversion of agricultural area into empty land. 133 xi LIST OF TABLES Table 3-1: Landsat satellite images used for the study. 60 Table 4-1: Model parameters in MIKE NAM. 66 Table 4-2: Weight of precipitation data used in Nong Son and Thanh My precipitation calculation.

70 Table 4-3: MIKE BASIN node corresponding to domestic water users. 72 Table 4-4: Irrigation nodes with corresponding irrigation area, precipitation, and meteorological station data. 76 Table 4-5: Land planning changes in Quang Nam and Da Nang until 2020. 83 Table 4-6: Description of land cover class classification.

84 Table 5-1: Drought and water shortage years from literature. 91 Table 5-2: SWSI value in year 1998 for Nong Son and Thanh My catchments. 92 Table 5-3: MIKE NAM corresponding NASH-Sutcliffe value. 96 Table 5-4: Calibrated MIKE NAM parameters.

96 Table 5-5: Industrial water demand and corresponding node in MIKE BASIN. 98 Table 5-6: Domestic water demand in the study area (calculated based on Vietnam Ministry of Construction (2006)). 99 Table 5-7: Domestic and industrial water demand (calculated based on Vietnam Ministry of Construction (2006)). 100 Table 5-8: Agricultural water demand under baseline condition (m 3/s) .